The existence of infectious diseases such as AIDS and hepatitis has highlighted the danger to which medical personnel may be exposed when treating patients by means of catheter devices where a sharp needle tip is used to pierce the skin of a patient. Medical personnel have been infected by physical contact with, or accidental prick by an infected needle (needle-stick).
In order to protect medical personnel against inadvertent needle-stick, a number of solutions have been developed whereby a protective means incorporated within the catheter prevents physical contact with the needle after use and hence against inadvertent needle-stick.
One known device for protecting the needle after use is described in European Patent 5447501. In this document, there is described an infusion catheter assembly including a hollow needle having a sharpened distal tip for piercing the skin of a patient. In a ready-for-use position the needle passes through a hole in a rigid front part which houses a resilient member.
The resilient member is retained under tension by the needle flank and exerts a force substantially at right angles to the longitudinal direction of the needle. In its retracted position, that is, when the needle tip is moved back through and beyond the hole in the rigid front part and within a main housing, the resilient member biases the needle tip laterally to prevent reentry of the needle tip through the hole.
This device is a relatively simple and economic device and is effective to minimise the danger of inadvertent needle stick. However, a disadvantage of this known device is that once the needle tip is moved back through and beyond the hole in the rigid front part there is nothing to prevent blood from flowing through the hole and into the housing.
It is an aim of the present invention to provide means for protecting the tip of a needle forming part of a medical device which includes means for preventing or inhibiting the flow of blood into the needle protection means.